A biosensor is an analytical device for detecting a target molecule such as a biomolecule. Most biosensors are optical biosensors. An optical biosensor may include a metal which can absorb light and generate electron waves on the metal surface. The electron waves may occur at a specific angle and a specific wavelength of incident light, and thus are highly dependent on the surface of the metal. When a biomolecule attaches on the metal, a measurable signal may be generated.
Some biosensors are electrochemical biosensors. An electrochemical biosensor usually uses a catalyst as a probe. However, the applications of such an electrochemical biosensor are limited because the signal is low. New biosensors with higher signal to noise ratio are needed for accurate detection of target molecules of interest.